1. Field of the Invention
The present invention relates to an airplane fuel supply system that supplies fuel within a wing fuel tank to an engine via a collector tank, the wing fuel tank including a wing tip fuel tank, a central fuel tank, and a wing root fuel tank. Furthermore, the present invention relates to a method for assembling a wing pipeline that extends in the span direction and runs through a partition provided within an airplane main wing.
2. Description of the Related Art
A wing fuel tank provided in an airplane main wing has a plurality of sections that are divided in the span direction and communicate with each other. A fuel pump for supplying fuel to an engine is provided in each of the sections. When the airplane banks laterally in a state in which there is little fuel remaining in the wing fuel tank, fuel moves between the plurality of sections of the wing fuel tank, leading to a possibility that the fuel pump in an empty section does not function. Conventionally, the fuel delivery volume (discharge capacity) of each of the fuel pumps provided in the respective sections is set larger than the fuel delivery volume that is necessary to run the engine so that the engine can run when at least one fuel pump operates.
However, providing a plurality of fuel pumps corresponding to a plurality of sections of a wing fuel tank and setting the discharge capacity of each fuel tank larger than the fuel delivery volume required by the engine as in the conventional arrangement, make the total discharge capacity of the plurality of fuel pumps extremely large.
Furthermore, since a fuel supply system wing pipeline and a vent system wing pipeline are provided in a fuel tank disposed within an airplane main wing and these wing pipelines are long members extending in the wingspan direction, it is impossible to assemble the entire pipelines in one step through an access hole provided in the main wing surface. Conventionally, a long wing pipeline is divided into a plurality of pipelines, the divided pipelines are inserted respectively through a plurality of access holes provided in the main wing surface, and they are then integrally joined via joints within the main wing.
However, it is difficult to carry out the work to join the plurality of pipelines within the main wing through small access holes; not only are large amounts of labor and time required, but also the reliability of seals in the joined areas deteriorates, leading to the possibility of fuel and air leaks. If the size and the number of access holes are increased in order to avoid the above, problems such as increases in the weight and air resistance occur.
The present invention has been achieved in view of the above-mentioned circumstances, and it is a first object thereof to reduce the weight and the pump drive force of a fuel pump by minimizing the size thereof while ensuring that a required amount of fuel is supplied to an engine.
Furthermore, it is a second object of the present invention to carry out the work of assembling a wing pipeline within an airplane main wing easily and reliably.
In order to accomplish the first object, in accordance with a first aspect of the present invention, there is proposed an airplane fuel supply system that includes a wing fuel tank formed from a wing tip fuel tank, a central fuel tank, and a wing root fuel tank which are disposed within an airplane main wing, a flapper valve that allows fuel movement from the wing tip fuel tank to the central fuel tank and restricts fuel movement in the opposite direction, another flapper valve that allows fuel movement from the central fuel tank to the wing root fuel tank and restricts fuel movement in the opposite direction, a collector tank that supplies fuel to an engine, a wing tip fuel pump that supplies fuel within the wing tip fuel tank to the collector tank, a central fuel pump that supplies fuel within the central fuel tank to the collector tank, and a wing root fuel pump that supplies fuel within the wing root fuel tank to the collector tank, and when the fuel delivery volume of the wing tip fuel pump is represented by Vt, the fuel delivery volume of the central fuel pump is represented by Vc, the fuel delivery volume of the wing root fuel pump is represented by Vr, and the fuel delivery volume from the collector tank to the engine is represented by Ve, the fuel delivery volumes Vt, Vc, Vr, and Ve are set so as to satisfy relationships Vr greater than Ve, Vt+Vc greater than Ve, and Vc less than Ve.
In accordance with such an arrangement, the fuel delivery volume Vt of the wing tip fuel pump, the fuel delivery volume Vc of the central fuel pump, the fuel delivery volume Vr of the wing root fuel pump, and the fuel delivery volume Ve from the collector tank to the engine are set so as to satisfy the relationships Vr greater than Ve, Vt+Vc greater than Ve, and Vc less than Ve. Therefore, when the airframe banks laterally in one direction causing the flapper valves to open and the fuel to collect in the wing root fuel tank, the fuel can be supplied to the engine without any problem by means of the wing root fuel pump whose fuel delivery volume Vr is larger than the fuel delivery volume Ve required by the engine; and when the airframe banks laterally in the other direction causing the flapper valves to close and the fuel to be trapped in the wing tip fuel tank, the central fuel tank, and the wing root fuel tank, the fuel can be supplied to the engine without any problem by means of the wing tip fuel pump and the central fuel pump whose fuel delivery volumes Vt, Vc are in total larger than the fuel delivery volume Ve required by the engine. In this way, at least the fuel delivery volume Vc of the central fuel pump can be made smaller than the fuel delivery volume Ve to the engine while enabling the supply of the required volume of fuel to the engine, thereby reducing the size of the central fuel pump.
Furthermore, in accordance with a second aspect of the present invention, in addition to the first aspect, there is proposed an airplane fuel supply system in which the fuel delivery volumes Vt, Vc are set so as to satisfy a relationship Vt=Vc.
In accordance with such an arrangement, since the fuel delivery volume Vt of the wing tip fuel pump and the fuel delivery volume Vc of the central fuel pump are set equal, the size of the wing tip fuel pump can be reduced in the same way as for the central fuel pump. Moreover, the use of identical specifications for the wing tip fuel pump and the central fuel pump can achieve a reduction in cost.
In the above-mentioned first and second aspects, a left collector tank TCL and a right collector tank TCR of an embodiment correspond to the collector tank of the present invention, a left wing fuel tank and a right wing fuel tank of the embodiment correspond to the wing fuel tank of the present invention, and a left main wing WL and a right main wing WR of the embodiment correspond to the main wing of the present invention.
Moreover, in order to accomplish the second object of the present invention, in accordance with a third aspect of the present invention, there is proposed an airplane wing pipeline assembly method for assembling a wing pipeline that runs through a partition provided within a main wing of an airplane and extends in the span direction, in which a wing pipeline that is made into a linear unit in advance is inserted in the span direction through an access hole provided in a wing tip and is fixed in a predetermined position.
In accordance with such an arrangement, the wing pipeline that is made into a linear unit in advance is inserted in the span direction through the access hole provided in the wing tip and fixed in the predetermined position. Therefore, the work of joining a plurality of divided pipelines within a main wing can be reduced, thereby greatly improving the workability, and the improved workability can enhance the reliability of the wing pipeline, thereby preventing the occurrence of fuel leakage and air leakage. Moreover, the size and the number of access holes provided on the main wing surface can be reduced, thus contributing to a reduction in the weight and the air resistance.
In the third aspect, a vent line 57 of the embodiment corresponds to the wing pipeline of the present invention, and a left main wing WL and a right main wing WR of the embodiment correspond to the main wing of the present invention.
The above-mentioned objects, other objects, characteristics, and advantages of the present invention will become apparent from an explanation of a preferred embodiment that will be described in detail below by reference to the attached drawings.